Chiller changeouts

[rotaryfrk]

I have (2) Powerchill natural gas driven 125ton water cooled chillers scheduled to be changed out over the winter. At another building I have (2) 125 ton water cooled york screws that seem to work very reliably, I'd like to stick with York but it seems I won't have any say on what I end up with. What brand or style should I stay away from? The (2) powerchills were installed in 98 and they were a mess from day one, I'd like to avoid anymore experimental equipment that I have to maintain.

[Healey Nut]

Its hard to stop a Trane , but then again I"m biased.

[rotaryfrk]

I've also found that it's NOT hard to underbid Trane equipment. I like Trane, would love to see two of them sitting in my mechanical room. But realistically it will probably be a Carrier.

[jd 07]

http://multistack.com

[Healey Nut]

Before you can wreck you have to get going ,something I dont think Multistack is capable of. just a thought

[absrbrtek]

The water cooled Multistacks have some serious issues with the condensers fouling/plugging up. Even with pristine condenser water they still have issues. Cleaning them is a major project. No way would I reccomend them. JMHO
http://multistack.com

[absrbrtek]

The carrier 30HX screw is a nice machine IMO for that tonnage range. Just get the comfort link controller mounted on the chiller so you know whats going on. I see very few problems with these chillers besides lack of maintanence.
I've also found that it's NOT hard to underbid Trane equipment. I like Trane, would love to see two of them sitting in my mechanical room. But realistically it will probably be a Carrier.

[rotaryfrk]

ABSRBRTEK whats your opinion on the Mcquay magnetic frictionless bearing machine? Had a salesman quote me a price on one last year. Seemed like it was experimental, at least the way he talked about it. I've heard of the technology but I don't want to get another pile of garbage that I have to maintain. Our current ones are a money pit.

[chiller rob]

i cant resist...
the carrier hxc is a nice unit we have many of them... those chiller have been good to use... it is still a screw... get some sound blankets too...

rotaryfrk... you are in tuborcor territory... this tonnage is a real good fit... any thing small and water cooled...

i got to get this out there... i just started up a retrofit... we built the skid in house disassmbled in pieces and installed in a 15 - 20 year old 16 story high rise to service 2 floors...

existing was 2 30 ton dx evap circuits per floor... common condenser water from tower on roof... we installed one 120 ton t-cor... one 120 ton shell and tube condenser and piped the liquids to that floor and the floor below, common suction back to the compressor... changed out the txv's with exv's stayed R22

with a moderate/ light load i am pulling 20 - 50 amps on the compressor... that is 10 - 25 amps of compressor power per floor... in my area that is the load for 65% of the year

the old recips fla was 46...

standing next to the compressor, (while running) you can hear me type... and yes i have good discharge temp.

i know this is new tech but we applied it old school and it is working good...

i dont want to take any thing away from factory machines but sometimes you just have to build it yourself!

Cheers!

[chiller rob]

for an alternative package vendor check out smardt...

[absrbrtek]

I have not had enough exposure on them to comment one way or another. Parts like boards are real expensive if out of warranty.
ABSRBRTEK whats your opinion on the Mcquay magnetic frictionless bearing machine? Had a salesman quote me a price on one last year. Seemed like it was experimental, at least the way he talked about it. I've heard of the technology but I don't want to get another pile of garbage that I have to maintain. Our current ones are a money pit.

[rotaryfrk]

When you say get the "comfort link" on the carrier chiller are you referring to the user controller that allows you to scroll and see what your temp and pressures are, along with all the other goodies they allow you to see?

If that is what your talking about my next question would have to be is this an "add on"? On our York Milleniums we have the display on the front of the controls panel. I figured they came with this feature automatically. Seems like it would be a piece of crap without it. Thanks for all the info.

[absrbrtek]

It comes with the machine as GB states.

[gyhooyabat]

Any of the 30 Series Chillers come with a marquee display to access any and all of the configuration points. The screw chillers, like the HXC and XA, all come with the Navigator display. The navigator display is easier to read and it is protable, so you can hold the display in your hand and walk around the machine to do your diagnositcs.

[absrbrtek]

Well thanks for straightening me out John. I'm trying to pimp your product here, about time you showed up. :)

[gyhooyabat]

Thanks Abs. Will try to visit more often. :D

Hey Rot, if you would like, email me and I'll send you the literature and a small power point on how the navigator or the marquee display work.

[rotaryfrk]

Sounds good GB, I've been looking at the link you have on your profile. The Evergreen looks like probably it would be a good choice. The thing that sucks is I don't have any say on what will eventually be installed??? Design/build rush job.

[heaviwall]

Look @ the york YCWS water cooled screw chiller multiple compressors on it Have not had any problems with them

[phixitman]

The Carrier HX and HXA have performed well for us. Keep up with the oil filter
replacement recommendations and keep in mind that the water cooled machines
do not like low condenser water temps. Install optional condenser water reg valve

[rotaryfrk]

I've had probs with the klixon CT's on the two YCWS that I have. Took many Techs before The York Tech switched the settings to keep it from locking out on Low curr M/P H/P. And yes change the oil filters on you'll get a "low oil pressure diff". Since the last visit from the York tech the YCWS have been running fine.

[rotaryfrk]

I saw a preliminary cut sheet that the general contractor received from our department.

It listed (2) specific chillers a Carrier 30HXC Screw machine and a Mcquay WGZ scroll machine.

Of the (2) listed pieces of equipment I'd much rather see the Carrier be installed.

I'd like to gather some pro's and con's about both these machines so I can let the powers that be make an informed decision rather than going with the cheapest costing machine.

Thanks for any and all feedback.

[emcoasthvacr]

See whether the contractors recover the refrigerant in tanks when doing the changeover. Like RTU's, most of the contractors just vent the refrigerant because it's quicker and cheaper.

[turbomaster]

I had some exposure to Mcquay scroll chillers last year '06 models. The micro navigation left a lot to be desired. I guess if you got used to it it would become old hat but it sure seemed way too complicated for a little scroll chiller. The controls looked kinda rinky dink too, lots of marginally sized wire and terminal blocks. I can't remeber for sure but I think they had Copeland scrolls. Those HXC machines are pretty good, a little noisy though but then what screw is not.

Mike

[drivewizard]

I've had probs with the klixon CT's on the two YCWS that I have. Took many Techs before The York Tech switched the settings to keep it from locking out on Low curr M/P H/P. And yes change the oil filters on you'll get a "low oil pressure diff". Since the last visit from the York tech the YCWS have been running fine.

I thought the oil filters were a life time filter, cuz they are not easily changed?

Could you explain how dirty filter could cause "low oil Diff", I could understand "High oil diff", but not low.
I thought a dirty filter would also cause slow or no loading of comp.
I thought "low oil diff" was generally due to cold tower water and no by-pass.
What am I missing???

[rotaryfrk]

The oil filters are very easily changed. And I am pretty sure they are not "lifetime" oil filters on these particular Screw machines.

The filters went 5 years before I started to get the "low oil diff" lockout, which requires a manual reset. I asked certain York techs on how frequently they need to be changed and they said not until it gives you any problems.

Anyway, I changed the rest of the oil filters on our second machine as a preventive measure. Very easy procedure.

[lirunaway]

The Carrier HX and HXA have performed well for us. Keep up with the oil filter
replacement recommendations and keep in mind that the water cooled machines
do not like low condenser water temps. Install optional condenser water reg valve

I agree:
A condenser water tower 3 way bypass valve for each chiller"Controlled by each chiller should be required. If it's not brine they can use a two way valve on the condenser water "leaving" the chiller "controlled by chiller" to cut cost. It works OK too.
Control companies of coarse like to control everything. The chiller controls it best looking at the temperature of the refrigerant condensing temperature of each circuit. The condenser refrigerant pressure pushes the oil. Not water.

Carrier requires control of the water pumps for warranty. If a freeze condition develops we can't be responsible if we can't turn the pumps on to protect the chiller. The chiller sends out 120v to pull in the pump starter. Pump interlock wires run through the starter auxillary contacts, through "EXTERNAL" flow switch and back to chiller. Many contractors believe the salesmen and bet the $100,000 on one internal switch. They are not around after the one year warranty period. If there is a control system interupting these signals then the controls company is liable.
The tubes are thinner for effieciency and require a 20 mesh strainer within 10' feet of each water bundle.

I go to start these machines all the time and there is no headpressure control, the strainer (if there is one) is on a pump on the other side of the plant, open the panel to see a bare terminal block, the manuals missing and machine must be started now. It happens more with chiller changeouts because the old R22 chillers didn't have pumpdown cycles. The old chiller started when the flow switch made.

You may not be able to choose the equipment, but you can oversee the installation and ask the right questions so it doesn't become another "problem from day one."

[jemawalton]

See whether the contractors recover the refrigerant in tanks when doing the changeover. Like RTU's, most of the contractors just vent the refrigerant because it's quicker and cheaper.

Must not be to worried about EPA audits and fines.

[Crazy4thenucks]

The HXC Carrier chillers are very nice. the comfort link system is very easy to use. The screws arent noisy at all. Installed one a year ago, with a sound enclosure, ended up taking it apart becasue the chiller actually ran quiter than the Carrier D class centrifugal it replaced.